Conceptual Site Model - Argonne National Laboratory

WVDP Phase 1 CSAPA complete (100%) logged gamma walkover survey (GWS) will be conducted for accessibleareas within WMA 5. Examples of areas that would not be accessible are areas where standingwater is present in wetlands, existing building footprints, and building pads. Based on the GWSresults, surface soil within WMA 5 will be divided four categories: (1) surface soils where GWSdata indicate contamination above CG w requirements; (2) surface soils where GWS data indicatecontamination, but it is not clear if contamination exceeds surface soil CG w requirement; (3)surface soils where GWS indicate impacts, but those impacts are not expected to exceed surfacesoil CG w standards; and (4) surface soils where there is no indication of impacts abovebackground conditions. The purpose of this data collection is to provide insights into the spatialdistribution of surface contamination, and to guide subsequent soil sampling. [required]E.9.3Surface Soil SamplingSurface soil sampling will be used to address areas inaccessible to GWS data collection, toresolve hot spots identified by the GWS data, and to evaluate the presence, absence, and/or extentof surface contamination above surface soil CG w requirements based on GWS results.• Wetlands. It is possible that standing water will be present in wetlands that prevent GWSdata collection from those areas. Soil sampling will be required for wetland footprints andfor any other areas where standing water prevents the collection of GWS data. WithinWMA 5, this is most likely to occur in the northeast portion of the WMA.For every area where standing water or saturated soil conditions prevent GWS datacollection, systematic soil sampling will take place. For wetland areas less than 200 m 2 insize, one sample will be collected. For areas between 200 and 1,000 m 2 in size, onesample per 200 m 2 will be collected. For areas between 1,000 and 2,500 m 2 in size, fivesamples will be collected. For areas exceeding 2,500 m 2 in size, at minimum one samplewill be collected per 500-m 2 area. One sample will be collected from each locationrepresentative of a 0-15 cm depth interval. Samples will be collected to providesystematic coverage of the wetland of interest. [contingent]• Hot Spots. If GWS data indicate the presence of contamination that possibly exceeds“hot spot” (CG emc ) standards or an isolated elevated area is identified that appearsindicative of a discrete release, the location of concern will be sampled with a biasedRev. 1 E-13